So any freshwater river going into ocean could provide a continual source of hydrogen that can, in turn, be burned to produce electricity. Maybe even power it's own factory to compress the hydrogen for later energy storage. Nice.

Like ethanol, this energy source also has the potential to be in conflict with a basic human need: fresh water. The world is already running short of fresh water even now, even though it doesn't yet make the news on a regular basis.Mixing fresh water with salt water to produce hydrogen on a large scale will be hard to contemplate while millions are dying of drought and thirst. Like most other "miracle" energy sources, there is always a fly in the ointment.

Aside from the fact that the places that *have* the drout are far away from the places that have huge amounts of fresh water... which is otherwise getting wasted because we can't do anything with it and so just let it go into the ocean without gaining anything from it.

Obviously, you wouldn't use this where there's a lack of water.. but where there's a *huge* amount going into the ocean(like, say, Washington state, etc... it could be practical.

I agree that there are problems with this idea, however one of those problems is not that "the world is running short of fresh water". Firstly this idea would not,in and of itself, consume any fresh water. This idea only works where fresh water is meeting the sea. Secondly fresh water is extremely abundant.... It just isn't always necessarily where we want it to be.

If only there was some way to turn that hydrogen back into freshwater after it's used to produce energy.

I wonder what the enviromental effects of moving to a hydrogen economy would be though? I mean, burning all that hyrdrogen would effectively dump water vapour into the atmosphere (and an updraught since most power generation is going to create heat in the area).. significantly more than before maybe? Perhaps people have already thought about this.

Actually this is not news, the first salinity based power station prototype was built in 2009 [statkraft.com]. What the summary should say is "Hydrogen proponents pretend to invent yet another technology". It seems to me that people in the hydrogen lobby produce a lot of stories in the vein "new inventions mean hydrogen IS in fact viable" whereas in reality all they are talking about is advances in electricity production or minute increases in the efficiency of hydrogen production which bring it closer to 50% thermal effic

Implicit in the lack of fresh water is the presence of obstacle to overcome that scarcity. Many of us living in first world countries take for granted a plentiful supply of cheap plastic and tinfoil or the existence of infrastructure that facilitate their creation, use, and safe disposal.

Often the places where people need water the most are also places that rains the least (or least conveniently). Fires require fuel, which is also not always available or cheap.

How does that help someone in a desert climate? Or how about someone that is hundreds of miles from the ocean? Even better, an area that has had almost NO rain in the last 6 months with 100+ degree temperatures almost daily, causing a water shortage and the local lakes to start drying up?

The point is, water shortages occur despite the ease of converting rain water and salt water. If there is neither rain nor salt water it's kind of difficult to convert it to drinking water.

is how much energy does it take to produce the membrane, what is their effective live span, and are you actually 'producing' any energy. Hopefully with the boost from the waste feeding bacteria the answer is yes.

like all the past bacterial solutions, it's growing them in mass that is the limiting factor. now, if they can alter some of these bacteria to divide continuously to make non-dividing bacteria then it will be a serious solution.

Wow. It's the obligatory "New discovery of an inefficient solar energy collection system using [seawater, algae, corn, etc.] whose output is [hydrogen, hydrocarbon lipids, alcohol] which [wrecks metal machinery, doesn't scale and has an EROEI is either barely over 1, or sometimes less]."

Man, it's been over a week since I read one of those. Guess we don't have to worry about that pesky cheap, high-EREOI hydrocarbon depletion thing now.

The freshwater doesn't magically appear and it isn't free. Solar energy create the weather that lofts all that freshwater into the atmosphere so that it can return as rain and enter a river and make its way back to the interface with that saltwater.... where we can create a system to turn it into hydrogen.... or we could just capture the solar energy more directly and turn it into electricity and use it!

...or we could just capture the solar energy more directly and turn it into electricity and use it!

We could. However, nature will continue to do its thing regardless of what we're also doing. The question is, can we also benefit from what nature is doing and is going to keep doing regardless, or is it not economically feasible to benefit from nature's efforts? If there is some efficient way to harvest nature's bounty here, we'd be fools to let the energy go to waste, unless harvesting it causes some significant harm or is simply not cost effective.

Yeah it's true. I was over reacting a bit to their use of the term "self powered". Also my BS sensors go off whenever anyone talks about using hydrogen as an energy source. First we need to use some kind of power to generate the hydrogen and then we still have the problem of packing it tightly into a fuel tank. The funny thing is that we already know exactly how to do that.... We call them hydrocarbons and they are a very efficient hydrogen transport mechanism. If only it weren't for those pesky carbon

You can say the same about hydro, wind, or wave energy, or even fossil fuels if you like. Basically every energy source we have apart from nuclear & geothermal, ultimately derives from the sun.

The important part is, can we harness it efficiently enough? Evaporation is already happening, over a vast surface area, and that's something we may be able to tap into more cheaply than via manufactured PV cells.

lol. Really, if you're going to need a small amount of current, then a small replaceable NiMH battery that the fuel cell can recharge would make LOTS more sense than something you have to maintain like this? I don't get it...

The MFC community isn't large, however had an online discussion forum going for four years now over at Yahoo, http://tech.groups.yahoo.com/group/MicrobialFuelCells/ . It has many academics on it, but is not unfriendly to the hobbyist. MFCs are one of few the areas of alternative energy and biotech in which it is relatively easy and inexpensive for beginners to get a functional device. I am not saying that the area of study is trivial, because there's a difference between something functional and something notable for its efficiency. But you can "muck about" in it. If this type of thing interests you, please come join us!

Especially when "all it takes is some membranes". There is a way to use a similar process, and make fresh water out of sea water- it is called 'reverse osmosis', it is brilliant, slow but otherwise efficient and it pretty much works on its own and yields -at a naive first look- huge amounts of free fresh drinkable water. But the membranes involved are the ones that do all the trick, and they are pretty damn expensive to acquire and maintain.

Let me point out yet another round of pseudo-scientific articles with sensational headlines. This time it is the term "self-powered" which implies to the layman that it is "free energy" or "perpetual motion" when in reality it is "salt-powered" as it requires a constant supply of saltwater and freshwater.